首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   859篇
  免费   44篇
  国内免费   35篇
耳鼻咽喉   1篇
儿科学   23篇
妇产科学   9篇
基础医学   84篇
口腔科学   15篇
临床医学   77篇
内科学   119篇
皮肤病学   9篇
神经病学   48篇
特种医学   183篇
外科学   85篇
综合类   27篇
预防医学   74篇
眼科学   29篇
药学   56篇
中国医学   1篇
肿瘤学   98篇
  2022年   6篇
  2021年   20篇
  2020年   5篇
  2019年   13篇
  2018年   17篇
  2017年   9篇
  2016年   11篇
  2015年   16篇
  2014年   24篇
  2013年   21篇
  2012年   41篇
  2011年   36篇
  2010年   37篇
  2009年   52篇
  2008年   43篇
  2007年   58篇
  2006年   50篇
  2005年   43篇
  2004年   30篇
  2003年   21篇
  2002年   19篇
  2001年   21篇
  2000年   14篇
  1999年   35篇
  1998年   30篇
  1997年   37篇
  1996年   25篇
  1995年   14篇
  1994年   9篇
  1993年   13篇
  1992年   9篇
  1991年   7篇
  1990年   12篇
  1989年   16篇
  1988年   25篇
  1987年   15篇
  1986年   10篇
  1985年   7篇
  1984年   4篇
  1983年   7篇
  1982年   3篇
  1981年   9篇
  1979年   6篇
  1978年   4篇
  1977年   4篇
  1975年   5篇
  1974年   5篇
  1973年   3篇
  1970年   3篇
  1962年   3篇
排序方式: 共有938条查询结果,搜索用时 125 毫秒
81.
A new tray has been designed for use during procedures involving needles and other sharp objects. The tray includes a foam adhesive pad, marked into 10 sections, into which the sharp objects can be placed point first. After the procedure, the objects can be safely withdrawn by their handles and then discarded. The tray has been used in more than 250 procedures.  相似文献   
82.
Zusammenfassung  1. Der Anforderungskatalog der Kassen?rztlichen Bundesvereinigung an Datenbanken und Software für Vertragsarztpraxen als Grundlage für eine wirtschaftliche Verordnungsweise bewegt sich in dem ihm vom Gesetz vorgegebenen Rahmen. 2. Eine doppelt belegte Funktionstaste einer Arztsoftware zur Verordnung von Arzneimitteln, die bei Eingabe des Codes für die diagnostische Erkrankung die ?ffnung eines Werbefensters mit einem Verordnungsvorschlag für das beworbene Medikament ausl?st, vermischt in unzul?ssiger Weise Werbung und Funktion.  相似文献   
83.
84.
85.
Tongue and oropharynx: findings on MR imaging   总被引:6,自引:0,他引:6  
Ten healthy subjects and 44 patients with diseases of the tongue or oropharynx were studied with magnetic resonance (MR) imaging. Axial, coronal, and sagittal images with a thickness of 4 mm were obtained with a pixel size of 0.75 X 0.75 mm on a 256 matrix. Nineteen of the patients underwent computed tomography (CT). Nine of those patients later had surgery, and the specimens were obtained for organ sectioning. These three studies as well as clinical history and physical examination findings were correlated. MR imaging was equal to or better than CT in those patients having both examinations. However, neither CT nor MR allowed recognition of histologic features or detection of microscopic spread of disease. Direct coronal and sagittal imaging planes on MR imaging allowed visualization of intrinsic tongue musculature, not possible with CT; this was important in recognizing subtle tumor extension. For these reasons, MR is the imaging method of choice for studying diseases of the tongue and oropharynx.  相似文献   
86.
A new thermodilution method for frequent (near continuous) estimation ofcardiac output, without manual injection of fluid into the blood, was tested.The method utilizes a pulmonary artery catheter equipped with a fluid filledheat exchanger. The technique is based on cyclic cooling of the blood in theright atrium and measurement of the temperature changes in the pulmonaryartery. Using this technique, a new estimate of cardiac output can be obtainedevery 32 s. Cardiac output estimates, obtained for a running mean of threemeasurements with this method, were compared to the mean of three conventionalthermodilution measurements. The measurements were obtained during shortperiods of stable respiration and circulation.In six pigs, we made 46 paired measurements of conventional thermodilution(TD) and near continous (TDc) thermodilution. The cardiac output(CO TD) ranged from 2.4–13.7 l/min (mean 5.4 l/min). Thebest linear fit through the paired data points was CO TDc =–0.57 + 1.01 CO TD. The mean difference between themethods was –0.50 l/min (S.D. = 0.39). The mean coefficient of variationof repeated measurements with the near continuous thermodilution was3.6%.Considering changes of more than 0.25 l/min to be significant, all changes incardiac output measured by conventional thermodilution were followed by therunning mean of three near continuous thermodilution estimates.This study demonstrates the feasibility of the new method to monitorcardiac output, and to detect all changes greater than 0.25 l/min.  相似文献   
87.
目的:观察含0.02%吡格列酮的饲料对NOD鼠糖尿病发病率的影响,分析巨噬细胞在吡格列酮预防NOD鼠糖尿病中的作用。方法:实验于2003-01/2005-01在中南大学湘雅二医院动物实验室及中心实验室完成。4周龄NOD雌鼠56只,随机数字表法分为吡格列酮组(n=25)和对照组(n=26),分别摄食含0.02%吡格列酮的混合饲料和普通营养饲料。自10周龄开始,每周测尿糖1次,尿糖阳性后用血糖仪测血糖,连续两次血糖≥16.7mmol/L即诊断为糖尿病。两组各取12周龄NOD雌鼠15只,处死前4d腹腔注射30g/L的硫代乙醇酸钠2mL,麻醉后摘除眼球法处死小鼠后腹腔灌洗收集巨噬细胞,加入脂多糖共同培养24d后收集上清,ELISA法测细胞因子肿瘤坏死因子α、白细胞介素6水平。结果:小鼠56只全部进入糖尿病发病率分析;进入腹腔巨噬细胞肿瘤坏死因子α、白细胞介素6的水平结果分析20只。①30周龄时,对照组25只小鼠有20只发生了糖尿病,发病率80.0%,平均发病时间为(139.2±38.2)d;吡格列酮组26只中有14只发生了糖尿病,发病率为53.8%,平均发病时间为(153.0±28.1)d,与对照组相比,吡格列酮组发病率明显降低(P<0.05)。②12周龄时对照组NOD鼠腹腔巨噬细胞肿瘤坏死因子α、白细胞介素6水平与吡格列酮组差异无显著性意义[(537.4±112.49),(448.9±92.18)ng/L;(551.2±108.23),(461.7±80.49)ng/L,P>0.05]。结论:吡格列酮在一定程度上预防和延缓NOD鼠糖尿病的发生;吡格列酮对NOD鼠糖尿病和胰岛炎的预防作用可能与巨噬细胞无明显关系。  相似文献   
88.
BACKGROUND: Platelets become activated during storage, which results in secretion of granules, vesiculation of microparticles, secretion of protein, and a number of other biochemical and morphologic processes that decrease the utility of platelet concentrates stored for transfusion. STUDY DESIGN AND METHODS: To evaluate the quality of stored platelet concentrates, the cell surface expression of specific activation-dependent antigens (CD62 and lysosome-associated membrane proteins 1 and 2 [LAMP-1, LAMP-2]) on platelets stored in a hospital blood bank over a 7-day period was examined. Relative microparticle counts and the expression of CD62 by microparticles, as well as platelet concentrate supernatant levels of soluble CD62, were determined. RESULTS: The percentage of platelets expressing CD62 increased significantly from Day 1 to Day 5 (p < 0.05) of storage; the mean fluorescence values for CD62 did not. In contrast, the mean fluorescence values of LAMP-1 and LAMP-2 rose significantly (p < 0.01 and p < 0.05, respectively) between Days 1 and 5. Significant declines in CD62, LAMP-1, and LAMP-2 percent expression and mean fluorescence were seen on Day 6 of storage (p < 0.001). Microparticle numbers increased significantly during storage and correlated with levels of CD62 protein (free and membrane-bound) (r = 0.95 vs. Day 2, p < 0.05; r = 0.88 vs. Day 5, p < 0.05). CONCLUSION: Flow cytometric evaluations of the expression of cell surface CD62, LAMP-1, and LAMP-2 are complementary tests that, especially when used in conjunction with the quantitation of CD62 protein, provided a simple and effective means of evaluating the quality of platelet concentrates stored for transfusion.  相似文献   
89.
Red cell alloimmunization in multitransfused HLA-typed patients   总被引:1,自引:0,他引:1  
The authors studied retrospectively the formation of clinically significant red cell (RBC) alloantibodies in 958 HLA-typed, multiply transfused patients receiving kidney (603 patients) or liver (263 patients) transplants or plateletpheresis transfusions (92 patients). RBC alloantibodies were found in 91 (9.5%) of these patients and multiple antibodies in 35 (3.7%). Rh (D, C, c, and E) antibodies accounted for 49 percent of the total and Kell antibodies for 31 percent. Antibodies were found in 15 percent of apheresis recipients and in 8.6 percent of renal and 9.5 percent of liver transplantation patients. No association was found between any HLA-A, HLA-B, or HLA-DR phenotype and the presence of RBC alloantibodies, either in general or when analyzed according to the specific antibody. Renal transplant patients with RBC alloantibodies were somewhat more broadly HLA-alloimmunized than were those without RBC alloantibodies. Patient gender did not affect these results. The authors concluded that the immune response to RBC alloantigens is independent of HLA type but is associated with an increased level of HLA antibody formation.  相似文献   
90.
It is not clear if low end-expiratory pressures contribute to ventilator-induced lung injury in large animals. We sought to determine whether ventilation with a low level of positive end-expiratory pressure (PEEP) worsens preexisting permeability lung injury in dogs. Lung injury was initiated in 20 mongrel dogs by ventilating with nebulized 3N hydrochloric acid until a lower inflection point (LIP) appeared on the respiratory system pressure-volume loop. One group of 10 dogs was then ventilated for 4 hours with PEEP set below the LIP (low PEEP), whereas the remaining group of dogs was ventilated for the same time period with similar tidal volumes but with PEEP set above the LIP (high PEEP). We found histologic evidence of reduced alveolar volumes in the low-PEEP animals. However, there were no differences in neutrophil infiltration, lung lobe weights, pulmonary capillary hemorrhage or congestion, or arterial endothelin-1 concentration between the 2 protocol groups. In conclusion, we were unable to demonstrate that ventilation with PEEP set below the LIP exacerbates hydrochloric acid-induced lung injury in dogs.  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号